This disclosure relates in general to a content delivery network (CDN) and, but not by way of limitation, to selection of an edge server for a CDN.
CDNs will use Anycast to find a point of presence (POP) that can deliver content hosted or cached by the CDN. To find the POP, a user computer will query a domain name service (DNS) that may or may not be close in network terms to the user computer. A POP can be assigned that is inefficient because the DNS was located in an unexpected place on the Internet masking the network location of the user computer. An inefficient POP negatively affects quality of service (QoS) perceived by the user. Anycast DNS is desirable because it is fast.
Anycast can be used to choose the edge server. The edge server is often in close network proximity to the location of the user's DNS and hopefully the user computer. During download of large files or playback of long streams, clients can have problems staying connected to an assigned edge server. Unexpectedly changing to another edge server because of Anycast route changes or server selection can interrupt the download or stream.
Within a network, HTTP proxy caches are used to relay information. In some cases, there are multiple layers of HTTP proxy caches to move a content object. Each extra hop of multiple proxy layers in a route consumes bandwidth. Ethernet bandwidth is relative plentiful, but can still become overloaded.